Proton-M Flies With Mexico's Satmex-8 Satellite—UPDATE

By Ben Evans

The Proton-M vehicle is rolled out horizontally to its launch pad. Photo Credit: Roscosmos

Hearts really were in mouths tonight, as a 191-foot-tall Proton-M booster roared aloft from Baikonur Cosmodrome in Kazakhstan, carrying Mexico’s Satmex-8 telecommunications satellite into geostationary orbit, more than 22,000 miles above Earth. Built by the Khrunichev Research and State Production Centre, the Proton—whose heritage extends back to the mid-1960s and whose record now encompasses 384 flights—is one of the world’s most reliable heavy-lift vehicles, being used both by the Russian government and by International Launch Services (ILS).

Today’s launch occurred at 10:07 p.m. Moscow Time (3:07 p.m. EDT), rising spectacularly into the darkened sky under the 2.3 million pounds of thrust produced by its six RD-276 first-stage engines. Upon reaching low orbit, over a nine-hour period, the Proton’s Briz-M upper stage executed five scheduled “burns” to inject Satmex-8 into its geostationary orbital home. All of these burns proceeded normally and without incident, demonstrating that the thrust shortfall problems experienced by the Briz-M during missions in 2012 appear to have been resolved. Separation of the Satmex-8 satellite into geostationary transfer orbit occurred at around 7:20 a.m. Moscow Time (12:20 a.m. EDT) on the morning of 27 March.

The Proton-M is the descendant of a vehicle which made its first flight in 1965. Photo Credit: Roscosmos

Destined to operate at 116.8 degrees West longitude, the 12,600-pound Satmex-8 was built by Space Systems/Loral (SSL), under a May 2010 contract to Satélites Mexicanos, S.A. de C.V. It arrived at Baikonur in November 2012 and is expected to augment an existing Satmex fleet by providing fixed satellite services in both North and South America. These services include broadband, voice, and data transmission and video broadcasting and will be enabled by an expansive communications payload of 24 C-band and 40 Ku-band transponders. Current plans estimate that Satmex-8 will remain operational for up to 15 years.

The Proton-M’s first stage—consisting of a central oxidizer tank, surrounded by six outboard fuel tanks, fed by the six RD-276 engines—provided the initial impetus for the launch of the new satellite. After burn-out and separation, the turn came of the second stage, whose four engines have a yield of 540,000 pounds, whilst the single-engine third stage produces 138,000 pounds. These three stages positioned Satmex-8 and its attached Briz-M upper stage on a suborbital trajectory. The Briz-M is capable of restarting up to eight times in flight, but was scheduled for only five burns on this mission.

According to NASASpaceflight.com, the early progress of the Briz-M in delivering Satmex-8 to geostationary orbit proceeded without incident, which is heartening as it comes only months after the dismal failure to loft Indonesia’s Telkom-3 and Russia’s Ekspress-MD2 satellites. Last August, a premature shutdown of the Briz-M left both satellites stranded in useless orbits, and another mission in December 2012 experienced a similar glitch, which impacted the Yamal-402 satellite. Today’s launch appears to have suffered no such ill-effects, with the first four burns concluded by 2:00 a.m. Moscow Time on the 27th (7:00 p.m. EDT on the 26th). The Satmex-8/Briz-M combo then coasted for more than four hours, ahead of the final burn, which lasted seven minutes, at 6:58 a.m. Moscow Time (11:58 p.m. EDT).

Ten minutes after leaving Baikonur, the Proton-M’s third stage separated, preparatory to the first of five Briz-M burns, which lasted 4.5 minutes and established the combo in a 107-mile circular parking orbit. Subsequent burns were scheduled to steadily raise this altitude to the intermediate orbit (170 x 3,100 miles), the transfer orbit (260 x 22,200 miles), and the geostationary transfer orbit (3,820 x 22,230 miles). The five Briz-M burns were timed to last between four and 18 minutes in individual duration.

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